<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>四则运算</title>
	</head>
	<body>
		<script>
			var num1 = parseInt(prompt("请您输入第一个整数"));
			var num2 = parseInt(prompt("请您输入运算符(1.+ 2.- 3.* 4./)"));
			var num3 = parseInt(prompt("请您输入第二个整数"));
			switch(num3){
				case 1:
				alert(num1 + num2);
				break;
				
				case 2:
				alert(num1 - num2);
				break;
				
				case 3:
				alert(num1 * num2);
				break;
				
				case 4:
				alert(num1 / num2);
				break;
				
				default:  
				alert("错误");
				break;
			}
		</script>
	</body>
</html>
